Increasingly, products are available to network service providers and enterprises alike that provide for and optimize the delivery of a variety of services including voice, data and video across wide area networks. In many instances, these wide area networks are connection-oriented, that is, a request is received for a connection through the network and a path is selected and established responsive to that request. Connection-oriented networks include many switches inter-connected by links, where each link may be provisioned to carry one or more trunks, where a trunk is for carrying a voice or data channel between switches. Unfortunately, network congestion can occur when a number of channels are routed through paths that use the same trunk. Alternatively, an entire network may become congested when all trunks are being utilized for connections.
Connection-oriented networks are particularly well suited to path-oriented traffic (switched voice, permanent voice, video, etc.) but connectionless data may also be carried on the same trunks. Although these networks may carry both voice and data traffic, a customer of a network service provider may consider that one type of traffic should have priority over the other. For example, the customer may wish to prevent or bump voice traffic from a particular trunk in preference to data traffic during times of congestion or high utilization. Voice connections that have been prevented access to, or bumped from, the particular trunk may be rerouted, if possible, through other trunks or over the Public Switched Telephone network (PSTN).
Typically, control of connections has been concerned with Quality of Service (QoS) guarantees, related to such factors as delay or reserved bandwidth on links along a path from source to destination, and not with the degree of congestion on a given network. However, as congestion increases in connection-oriented networks, there is a need for dynamic control of connections so that the networks may adapt to various congestion scenarios.